Circuit breaker contact



Aug. 26, 1947. A. s. cAswl-:LL

CIRCUIT BREAKEH CONTACT Filed April 4, 1944 4 sheets-sheet 1 .92 nw u l... 1 N0 s ,i @Ma www zmuw.

n m ma me m NTM/ver Aug. 26, 1947. Aps. cAswELL CIRCUIT BREAKER coN'TAcT 4 .Sheets-Sheet 2 Filed April 4, 1944 l n .ME

INV EN TUR.

erf/ue J. cmu/fu.

AT1-omer f ug. 26, 1947. A, s, CAswELL 2,426,387

CIRCUIT BREAKER CONTACT Filed April 4, 1944 4 Sheets-Sheet 3 INVENTOR.

APN/uf J nimma/ v Aug. 26, 1947. A. s. cAswELL CIRCUIT BREAKER 'CONTACT pril 4, 1944 4 Sheets-Sheet 4 Filet? A w am R ma W N f Wm w .im W N n A Y B 2-2 of Figure 1. Figure 3 is a cross-sectional view illustrating a Patented Aug. 26, 1947 CIRCUIT'BREAKER CONTACT Arthur S. Caswell. Philadelphia, Pa., assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application April 4, 1944, Serial No. 529,439

My present invention relates to contact members, and more particularly to the stationary contact unit which provides in simplied form both for the main and arcing contact surfaces and, at the same time, is so arranged that a direct connection is made from the contact elements to the current carrying bus without the necessity of flexible pigtails or other types of easily worn out connecting members.

Also, my invention contemplates that the very elements which ensure proper current carrying relationship between the stationary contact members and the bus to which they are connected also ensure proper engagement between these stationary contact members and the movable contact unit.

An important object, therefore, of my invention is the arrangement ofdcontact members so that a direct current carrying connection is provided between the contact member and the bus on which they are mounted without the necessity for iiexible pigtails or other connecting elements which are usually subjected to wear and irequently require replacement and repair.

Another and important object of my invention also is the provision of biasing means with respect to the main and arcing contacts of a switch structure, which biasing means have a two=sold purpose: (l) to provide a direct current carrying connection between the main and arcing contacts and the bus on which they are mounted and (2) to provide appropriate contact pressure between these main and arcing contacts and the complementary contacts.

These and many other objects of my invention will become apparent in the following description and drawings in which:

Figure 1 is a cross-sectional view of a pair of complementary contact units embodying the principles of my invention.

Figure 2 is a cross-sectional view taken on line modified form oi! my invention.

Figure 4 is a cross-sectional view taken on line 4 4 of Figure 3 looking in the direction of the arrows.

Figure 5 is an expanded view in perspective of the contact structure of Figures 3 and 4.

Figures 6, 7 and 8 are schematic views showing respectively the closed, partially open and open position of a circuit breaker embodying the contact elements of Figures 1 and 2.

Referring now to Figures 1 and 2, I have here 2 Claims. (Cl. 20D-166) shown a stationary contact unit I0 constructed in accordance with the principles of my invention and a complementary movable contact member I2.

In the specific embodiment here shown, it is intended that the complementary contact member I2 be the movable contact and that it have an axial motion toward and away from the stationary contact structure I0. It will be obvious, of course, that in appropriate cases the contact member l2 may be the stationary contact unit, While the contact structure l0 be made the movable unit having the axial movement toward and away from the contact l2. It is preferred, however, that the structure l0 in this instance be the stationary one.

The stationary contact structure l! comprises a main current carrying member Il on which are secured the various elements of the contact.

The main current carrying member il may, of course, be a direct extension of the bus or an extension ci a back connection stud which is specifically formed to accommodate the various members. The front end of the current carrying member it is provided with a transverse slot I3 at the base of which a pair of recesses i5 and i6 are provided in order to position the compression springs and i9.

A pair of main contact housings 2@ and 2l are ranged so that it may slide in and out of the space 3l between the opposite housings 20 and 2 I.

The arcing contact member 30 is a. member of substantially rectangular cross-section having at its outer surface an arcing contact tip 32 and having at its'innermost end a pair of opposite anges'34 and 35 which are designed (at the end of the path of travel'of the arcing contact member 30) 'to bear against the flanges 28 and 29 to prevent further outward movement of the arcing contact member 30.

Arcing contact member 30 is provided with a pair of recesses 38 and 39 to receive the opposite ends of the compression springs I8 and i9. The

recesses 36 and 33 are thus in axial alignment with the recesses I and I6 in the end of the' main current carrying member II.

The arcing contact member 30 is, of course, of conductive material; while the contact tip 32 is of an appropriate arc resisting material.

The opposite flanges 34 and 35 of the arcing contact member 30 are in sliding nt with the side walls 40 and 4I of the slot I3. t i --An appropriate current carrying connection from the arcing contact 30 to the current carrying member II is provided `through the main contact members 50 and 5I hereinafter described.

It will, however, at present be clear that as the movable contact member I2 moves axially so that the movable arcing contact tip 43 moves into engagement wlththe stationary arcing contact tip 32, the arcing contact member 30 will be pushed up against the compression of the springs I6 and I9. At this point, the main contact surfaces 53 and 54 of the movable contact I2 will move respectively into engagement with the contact surfaces 55 and 56 of the main stationary contacts 50 and 5I.

Each of the housings 2li and 2| is provided with transverse slots 60 and 6I forming a chamber therein. y

The walls ofthe housings 20 and 2| are so formed as to provide reentrant ledges or flanges E2, 62 and 63, 63 at the open ends of each of the transverse slots 60 and 6I.

The main contact members 56 and 5I are each provided with apair of recesses 10, 10 and another pair of recesses 1|, 1I normal to the first pair of recesses 1li. Each of the pair of recesses 1l) in each of the main contact members 5301' 5I has its longitudinal axis normal to the main contact surfaces 55 or 56.. Consequently, compression springs 13, 13 in each of the recesses 1|I, compressed between the base of each recess 10 and the base 15 of each slot, drive the respective contact members 50 .and 5| inwardly toward the space 3|.

5I, each of these springs 60 being compressed Shoulders 11, 11 on each of the respective contact members 5I) and 5I bear against respective fianges 62 and 63 of the housings 20 and 2| to limit the movement of the contact members toward the space 3|. By this means, the contact members 50 and 5| are given appropriate contact'pressure;` that is, the springs 13 bias these contacts toward engagement with the main Contact surfaces 5,3 and 54 of the movable contact I2. Thus, when the movable contact I2 moves longitudinally into the space 3| between the main contact housings, first the arcing contact tip 43 engages the stationary contact tip 32, and on continued movement of the contact member I2, the stationary arcing contact member 30 is pushed back into theslot I3.

As the movable contact member I2 thus continues to move, the main contact surfaces 53 and 54 thereof move respectively into engagement with the main stationary contact surfaces 55 and 56. f

On completion of the closing movement of the movable contact member I2, the entire surface of each of the main stationary contact surfaces 55 and 56 is pressed respectively against the main contact surfaces 53 and 54. Appropriate contact pressure is obtained by means of the compression springs 13, as above described.

In order now that proper contact be made between the main contact members 50 and 5| and the current carrying member I I, compression springs 80, 80 are provided in each of the recesses between Ythe, base of the recess 1I in which it is located and the wall 82 of the housing. The

compression springs 80, therefore, drive the movable contact members 50 and 5I firmly toward the right and thus against the Wall 85, 65 of each of the housings and 2|. l

By this means, therefore, the contact members 50 and 5| are brought into close contacting engagement with the inner wall 35 of each of the housings 2|) and 2|; and since each of the housV ings 20 and 2| is itself closely held by means of the bolts and 26 against the face of the main current carrying member I I, a good current carrying path is providedfrom the main contact surfaces 55 and 55 to the current carrying member I I.

The utilization of the springs 13 and 30 which operate Iin directions normal to each other thus provides for good contact (in the case of springs 13) between the stationary and movable main contact surfaces and (in the case of springs 3|!) for good contact pressure between the main stationary contact members and the current carrying member I I.

By this means, therefore, the necessity for pigtail connections between the main stationary contact member and the main current carrying member is obviated. The connection between these members is obtained by simple spring pressure and by means of parts which are not subjected to flexing, bending, rotative tearing `or corrosive forces. f

Similarly, on contact separation, the current carrying path from the arcing contact member to the main current carrying member I is also lprovided by means of the main contact members and 5| which, by means of the spring 13, are pressed tightly against the sides of the arcing contact member 30 and which, therefore, in the manner previously described, establish a current carrying path to the main current carrying member I I.

During the opening of the circuit breaker when the movable contact member I2 moves down, the main contact surfaces 53 and 54 slide respectively with respect to the stationary main contact surfaces and 56. During this sliding movement, the sides of the stationary arcing contact move progressively into engagement with the stationary main contact surfaces 55 and 56.

When the main contact surfaces 5 3 and 54 of the movable contact member move out of en- Eagement with the `main stationary Contact surfaces 55 and 56, the arcing contact member 30 still has room for additional downward sliding motion, so that for this brief period of time during the completion of the downward movement of the arcing contact member 30, only the arcing contact surfaces 43 and 32 are in engagement.

When the arcing contact member 30 reaches its limit of movement, that is when the flanges 34 and 35 move against ledges 28 and 29, the arcing contact member 30 is halted and the arcing contact surfaces 32 and 43 separate on continued downward movement of the movable contact I2.

'I'he arc is then drawn between the arcing contact tips 32 and 43 which are designed to withstand the arcwhile the main contact surfaces 53 and 5i4l of the movable contact I2 and the main contact surfaces 55 and 56 of the stationary contact I0 are thus protected. i

The slots I3, 60, and 6I, which define the various chambers in which the arcing contact and the main contact members move, are fully enclosed (except at the contact ends) by means of the pair of side plates 90 and 9| which are positioned on each side of the stationary Contact member, as shown in Figure 2, to close 01T the ends of these slots.

The side plates 90 and 9| may be provided with ilanges 92 and 93 respectively which serve as additional securing members to maintain the housings 20 and 2| of the main contacts in appropriate position.

The main current carrying member I is provided with appropriate recesses 94 and 95 so that the side plates -90 and 9| may be properly positioned with respect thereto to present a iiush appearance.

The plates 90 and 9| may be secured in position in any suitable manner as, for'instance, by-bolts which engage not only the main current carrying member but also the sides of the respective housings 20 and 2|.

The side plates 90 and 9| simplify the replacement and repair of the main and arcing contacts. On removal of the side plates 90 and 9i, the main contact members 50 and 5| slide out from the ends of their respective slots 60 and 5|.

Similarly, an appropriate tool may then be entered into the slot I3 from the side to compress the springs I8 and I9 s0 that they may be withdrawn from the recesses I5 and i5, `and so that the arcing contact member 30 may be slid out sideways. y

When all of the elements are in position. they are secured in appropriate position by means of the side plates @il and 9 I.

By this means, a proper sequential operation is obtained during the separation of the contacts so that the main contacts separate ilrst andthe arcing contacts separate last.

It is obvious, of course, that the stationary and movable contacts may have any appropriate shape which may be suitableto the particular purpose. Thus, for instance, asseen in Figure 2, the movable contact member l2 is a substantially flat member having a single arcing tip lit. The arcing contact member 30 :need not necessarily be a single member of rectangular cross section; it is, in fact, preferred that it be two separated members, each of the said members being similar in form and half the Width of the movable contact member l2, and each of said members being separately biased by its respective spring i8 or i5. This will further ensure appropriate arcing contact pressure.

Similarly, each of the main stationary contacts 50 and 5| may be a single. member extending through the entire slot B or 5|; or they may be separate members each similar in form and in operation so that a pair of similar members on each side will further ensure main contact pressure; it is in fact preferred for the purpose of obtaining appropriate contact pressure in case of possible unevenness of the surfaces that two or more contact members i? or 5i be used alongside each other on each side.

In Figures 3, 4 and 5, I have shown a slight modification of the structure herein described wherein only one spring is needed With respect to the main stationary contacts to obtain both appropriate Contact pressure between the cornplementary contacts and to ensure a proper current carrying path from the main stationary contacts to the current carrying member.

In this case, the stationary contact structure ||0 is mounted as a unit in any suitable manner between side plates |||a and |||b, which are U-shaped bracket having the flange extenl sions |4|, |4| to receive the bolts |25.

Each of the housings |20 and |2| is provided with a front plate |85, |85l of conductive material secured thereto in any appropriate manner as, for instance, by the bolts |25a. The end of each of these plates |85 and the sides of each of the housing members |20 and |2| are provided with tapped openings |90, |90 to receive bolts |9|, 9| which pass through the extensions |||a and I||b of the main current carrying member for the purpose of securing the main stationary contact member ||0 tothe main current carrying member;

The housing member |20 (as well as the housing member |2|) and the plate |85 each deiine an open ended chamber |60, in which the respective main stationary contacts |50, |50 are housed.

Each oi.' the plates |85l is provided, adjacent the end thereof which defines the open space i 3| between the opposed main` stationary contacts, with a shoulder |53.

Each or" the main Contact members E50 is also provided with an extension .i'il which bears against the shoulder |63 and prevents the contactfrom being completely removed from the chamber 50 under the bias of the compression spring i113.

Compression spring |13 is mounted in a recess ill in a wall of the housing |20 (or |2|!) and bears against the base of the said recess. The opposite end of the compression spring |13 enters a recess |12 in the main stationary contact l50.

Recesses i12 and |1| are in axial alignment so that the spring |13 bears against the base of each of the recesses |12 and |1|.

` Each of the main contacts |50 is provided with a main contact surface |55, Each o the extensions |11 of each of the main contacts i5@ is provided with a contact surface |15.

It will be noted that the angle of the spring i'iii is such that it is substantially 45 to'each of the contact surfaces |55 and |15. y

Consequently, it will be noted that the compression spring |13 has two components; it drives cach of the main contact members toward the right so that each of the contact surfaces illii bears tightly against the inner surface of theplate H55, and, also, it drives each of the main contact members |50 toward the space |3i to obtain vappropriate contact pressure.

By this means, therefore, the single spring |13 of Figures 3 to 5 performs the function of the two springs 'di and 13 of Figures 1 and 2.

The arcing contact member |36 moves in the space itil between the opposite main contact surfaces E55. The upper end of the arcing'I contact E30 rides in the chamber I3 dened by the bracket |45 and the oppositely adjacent surfaces of the housings |25 and l2l.

A compression spring ||8 bears at'one end against the inner surface of the base of the U-shaped bracket |45, and at the opposite end enters the recess |38 in the arcing contact member |30.

The arcing contact member |30 is provided with opposite flanges |34 and |35 which bear against shoulders |28 and |29 of the housings |20 and |2|.

Flanges |34 and |35 thus limit the downward movement of the arcing contact member |30.

As is shown in Figure 4, the arcing Contact member |30 is made up of two separate units |30a and |3013. A separate spring H drives each of these units outwardly toward the right.

Proper current carrying pressure between the arcing contact units |d and |30?) and the plate extensions |||a and |||b is obtained by means of the transverse compression springs |05. These transverse compression springs |90 are positioned in opposite coaxial recesses |01, lill in each of the opposite units |30a and |30b and bear against the bases oi" these recesses to drive the arcing contact units |30a and |3013 apart, The outer surfaces of the arcing contact units i30a and |3017 are thus driven iirmly against the plates ills and |||b in order to obtain appropriate contact carrying pressure between them,

Each of the main contact members H on each side or' the space |3|, is .shown in Figure" 5, may be a compound unit consisting ol: separate members which. may likewise be d 1iven apart, so that the side surfaces bear st the plates Illa and |||b by means of an exactly similar arrangement of springs |00 positioned in exactly similar recesses lill'. Although this is desirable and preferred, it is not absclutelsi' essential since the spring |13 has the dual func-m tion of maintaining not only Contact pressure between the contacts but current carrying pres-- sure between the members |50 and the plate |05 which, in turn, is bolted to opposite plates |||o and |||b.

Likewise7 it is clear that, as was described in connection with Figures 1 and 2, the arcing contact member |30` may be maintained in appro-- priate current carrying relation with the plates |||a and |||b by reason of the .tact that the main contact surfaces bear against the sides of the arcing contact |30 asthe movable and staN tionary contacts separate.

As previously described, the arcing 'contact members |30 each have an arcing tip k|32 which engages a similar arcing tip |43 on the movable contact member l2.

The movable contact 4member ||2 is also pro-- vided with main contact tips |53,` |53 to furnish an appropriate current carrying engagement with the Contact tips |55 of the stationary main conw tacts |50.

During the closing of the circuit breaker of Figures 3 to 5, as the movable contact member |12 moves up, the arcing contact tip |43 first engages the arcing Contact tip |32 and the arcing contact |30 is moved up against thecompression of spring IIB. On continued upward movement of the movable contact ||2, main movable contact tips |53 move into engagement with the l stationary main contact tips |55 to complete the .of thestationary main contact members |50 has the dual function of maintaining proper contact pressure and of maintaining a proper current carrying path between the contact member |50 and the current carrying member of which the plates l la and- |b are extensions.

This dual function is accomplished by reason of the i'act that the spring |13 is set at such an angle with` respect to the contacting surfaces |15 and |55 as to have two components driving each of these respective contact surfaces in the proper direction to maintain proper current carrying relationship Abetween those surfaces and their complementary elements.

Ilzl'ere again, the utilization of the spring pressed stationary contact members, which are spring pressed not only into engagement wtih the complementary contact but also in engagement n. the curr nt carrying member on which they are noopt-ed, eliminates the necessity for pigtall connections or other 'types oi connections which may' then break, tear, or become corroded in op eration. Consequently, the cost oi maintenance A and. repair on these contacts is greatly decreased.

Likewise, the Contact structure of Figures 3 to 5 is readily removable and the elements thereof are readily replaceable.

The unit ||0 oi Figure 3 is a single integrated unit which may be inserted between the extensions l I la and Ib and bolted thereto and which may as readily be removed therefrom.

The only specic operation necessary other than the manipulation of the necessary bolts is to compress together the arcing contact elements |30a and |30b so that they may slide between the plates 1a and Ib. Once the unit |0 has been removed from between the plates |||a and lllb. each of the elements of the structure |0 is readily acceptable or examination, replacement, and repair.

lt is only necessary to remo-ve the bolts |25 and s to completely expose every single part of the unit; and conversely, it is only necessary to arrange the unit.in the form shown in Figure 5 and replace the bolts |25 and |25a to reintegrate the structure ||0 of Figure 3, then the structure as a whole may be placed between the current carrying plates |||a and Ib and thus be integrated with the circuit breaker.

In Figures 6, 7 and 8, I have shown schematically, the manner in which my novel contact members may be utilized in an air blast circuit breakerof the type shown in applications Serial Nos. 483,387 and 410,260 of William M. Scott, Jr.. and of William M. Scott, Jr., and Otto Jensen, flied April 17, 1943. and September 10, 1941, respectively, and assigned to the assignee of this application.

The contact members shown in Figures l and 2 are here used.

The movable contact member |2 is here shown as an extension of a piston 203 which moves in a cylinder 202 and is biased toward raised or contacting position by a spring. 20|. y The cylinder 202 and the entire contact structure is mounted on the air tank 204. On occurrence of predetermined circuit conditions, air. in the valve dome 2 |0 is released to permit the tank air pressurel to open valve 201 so that air may flow under pressure through passage 208 into cylinder 202. Air pressure drives down piston 203 to open-the contacts, while the air reaches up past the contacts in the arc chute- 205 to exhaust through the vents 206. This operation is more fully described in the applications above referred to.

The upper main stationary contacts and 50 and arcing contact v3l! are connected to the upper connection stud 2H.

The lower main stationary contacts 5| and 50 operate and are constructed in the same manner as do the upper ones and are connected to the 'lower connection stud 2|5.

The movable contact I2 acts as a bridge between the upper and lower contacts. The circuit is closed in Figure 6 and open in Figure 8. The intermediate secondary contacts 25| and 250 are spring biased inwardly to the center of the arc chute by means of springs 213, bearing between the base 2|2 of their respective housing 22| and 220 and th'e bases of the intermediate' contact members. They serve further to protect the main upper contact surfaces.

It may thus be seen that my invention may readily be incorporated in existing types of circuit breakers.

In the foregoing, I have described my invention and the basic principles thereof only in connection with the specific preferred embodiments. Many variations and modifications of these preferred structural embodiments within the spirit of my invention should now be obvious to those skilled in the art. Accordingly, I prefer to be bound not by the specic disclosures herein, but only by the appended claims.

I claim:

1. In a circuit interrupter, an electrically conductive contact block having a substantially central opening; additional openings in said contact block on opposite sides of said central opening; contact members mounted in said additional openings in said contact block on opposite sides of said central opening; means biasing each of said contact members into engagement with a wall of its opening in said contact block; said contact block bridging said Contact members on opposite sides of said opening; additional means biasing said contact members toward each other into said central opening; and stop elements for limiting the movement of said contactl members into said central opening.

2. In a circuit interrupter, an electrically conductive contact block having a substantially central opening; anadditional opening communicating with the central opening; a contact member mounted in said additional opening on said contact block; means biasing said contact member into engagementl with the wall of said additional opening in said contact block and into said central opening; and stop elements for limiting the movement of said contact members into said central opening.

ARTHUR S. CASWELL.

REFERENCES CITED The following references are of record in the le of this patent:

, `UNITED STATES PATENTS Number Great Britain Feb. 13, 1939 

